I got (strange looking E with d besides it) and but I havent found (strange E thing with d^2) I've tried to add it all and divide it by the total number (17). I tried to subtract after-before. I tried to times my answer of 123.5 by sum of all d (the stange looking E with d besides it). I have run out of ways to find it. Just to correct , the answer is 1716.9. I dont know how to get this. Helpppp